Mechanical stress of bones, such as that caused by weight lifting, is detected by
A. osteocytes, which then communicate to osteoblasts to increase synthesis of osteoid.
B. osteoclasts, which then communicate to osteocytes to increase the size of lacunae.
C. chondrocytes, which then trigger osteoblasts to increase bone in a lengthwise fashion.
D. osteoblasts, which then communicate to osteocytes and osteoclasts to deposit more hydroxyapatite.
A
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An area of the retina that contains only cones and is the site of sharpest vision is the
A) outer segment. B) inner segment. C) fovea. D) optic disc. E) tapetum lucidum.
Which of the following is NOT a vital sign?
A. Heart rate B. Temperature C. Odor D. Respiratory rate
Which is not correct regarding the innervation of the kidney?
A. Parasympathetic innervation is from the vagus nerve. B. The kidney is served by the renal plexus. C. Sympathetic innervation is from segments T10-T12 of the spinal cord. D. Sympathetic stimulation causes vasoconstriction of the renal blood vessels. E. Parasympathetic stimulation decreases the rate of filtrate formation.
Action potentials are normally initiated at the axon hillock because
a. there is a particularly high density of voltage-gated sodium channels there. b. threshold potential is lower there than at other sites along the plasma membrane. c. activation of sodium channels at the axon hillock results in a particularly strong inward current and consequent depolarization. d. all of these. e. none of these.